This invention relates generally to the field of vacuum brake boosters for cars or light trucks, and in particular, to an apparatus and method of attaching a connecting member and a tube member to a housing of a vacuum brake booster.
Vacuum brake boosters are typically used in automobiles and light trucks. They typically include a housing that includes a front side and a rear side. The rear side is typically attached to the firewall of the vehicle, while the front side provides an attachment for a master-cylinder. In order to fasten the vacuum booster to the firewall, rigid tubular members are provided, which extend through the front side of the housing, through the interior of the booster, and through the rear of the housing. Fastening bolts can then be inserted into the tubular members to allow the booster to be attached to the firewall.
Various arrangements are known for attaching a tubular member to the housing of a vacuum brake booster. An example of a conventional arrangement is shown generally in FIG. 10. As shown in FIG. 10, at least four parts are required: namely, a tubular member 100, a fitting 102, a nut 104 and a seal 106. One end 108 of the tubular member 100 is connected and sealed to the front side 110 of a housing 112 via the fitting 102 by slightly deforming the metal structure of the fitting 102. That is, the one end 108 of the tubular member 100 is crimped against the fitting 102, which itself is crimped against the front side 110 of the housing 112. The nut 104 and the seal 106 are positioned adjacent to an inner surface 114 of a rear side 116 of the housing 112. The nut 104 and seal 106 facilitate the connection and sealing of a second end 118 of the tubular member 100 to the rear side 116 of the housing 112. EP 0 623 081, for example, discloses a similar arrangement for attaching and sealing a tubular member to the front housing of a vacuum brake booster.
There are several disadvantages to this arrangement, including the number of parts required (i.e. the nut 104, and the seal 106). The increased number of parts in turn increases the costs associated with the vacuum brake booster. Moreover, the installation of these parts is a labor intensive and time-consuming process, which also increases the costs associated with installing the booster. In addition to the above, the crimping arrangement associated with the fitting 102 and the front side 110 of the housing 112 cannot be implemented to flush mount a rear side of a booster housing to a firewall due to the interference that would caused by the threaded fitting 102.
Another example of a conventional apparatus is shown in FIG. 11. As shown in FIG. 11, the tubular member 200 consists of a first tube portion 202 and a second tube portion 204. The first tube portion 202 is linked mechanically to a rear housing 206 and the second tube portion 204 is mechanically linked to a front housing 208. The bolt 210 may extend through the tubular member 200 from the front housing 208 to the rear housing 206. A flange 212 positioned adjacent to an end of the bolt 210 prevents the master-cylinder from compressing the booster. EP 0 331 535, for example, discloses a similar arrangement for providing a tubular member in a vacuum brake booster.
There are also several disadvantages to this arrangement. For example, it is very impractical and difficult to manufacture and assemble the first and second tube portions 202, 204 so that they are a part of the housings 206, 208, respectively. This arrangement is also likely to require additional parts. The large number of parts required, and the complexity of the interconnections between parts, also results in increased costs.
Another example of an apparatus and method of assembling a brake booster is shown in U.S. Pat. No. 5,487,327 (xe2x80x9cthe ""327 patentxe2x80x9d). FIGS. 2 and 3 from the ""327 patent are reproduced herein as FIGS. 12A and 12B. As shown in FIGS. 12A-12B, the booster housing is assembled by first inserting an end portion 52 of the spacer 50 (i.e. tubular member) into a recess 40 of a connecting member 32. The connecting member 32 is then passed through a fastening hole 30. The two tool members B and C are compressed, which simultaneously crimps the connecting member 32 with the housing 26 and the spacer 50. FIG. 12A shows the apparatus before crimping, while FIG. 12B shows the apparatus after crimping. The disadvantage of this arrangement is that it cannot be used to mount a rear side of a booster housing flush with the firewall of the vehicle.
Accordingly, it would be desirable to have an apparatus and method of attaching a connecting member and a tube member to a housing of a vacuum brake booster that overcomes the disadvantages described.
One aspect of the invention provides a connecting member including a cylindrical body portion having a first end and a second end. A rim portion is formed between the first end and the second end, and a stem portion is formed at the second end of the cylindrical body portion. The stem portion includes a tapered end portion to allow the stem portion to flow radially outward when a force is applied to the stem portion. The cylindrical body portion further includes a first opening formed in the cylindrical body portion adjacent to the first end of the cylindrical body portion for receiving an end portion of tube member. The cylindrical body portion also includes a second opening in communication with the first opening. The first opening has a first diameter and the second opening having a second diameter, the second diameter being less than the first diameter. The stem portion is adapted to be deformed to create a seal between a portion of a housing member and the connecting member. The rim portion and the stem portion may preferably define a recess to receive the housing member. The rim portion may preferably extend outward from the cylindrical body portion in a direction towards the second end. In particular, the rim portion may preferably extend outward from the cylindrical body portion approximately 25 degrees from vertical. The cylindrical body portion may be formed from a single piece of rigid material.
Another aspect of the invention provides a vacuum brake booster including a housing member and a connecting member including a cylindrical body portion. The cylindrical body portion includes a first end and a second end. A rim portion is formed between the first end and the second end, and a stem portion is formed at the second end of the cylindrical body portion. The stem portion includes a tapered end portion to allow the stem portion to flow radially outward when a force is applied to the stem portion. The cylindrical body portion further includes a first opening formed in the cylindrical body portion adjacent to the first end of the cylindrical body portion. The cylindrical body portion also includes a second opening in communication with the first opening. The first opening has a first diameter and the second opening has a second diameter. The second diameter is less than the first diameter. The stem portion is deformed to create a seal between a portion of a housing member and the connecting member. A tube member includes a first end portion, which is received in the first opening of the cylindrical body portion. An outer surface of the stem portion may preferably be flush with an outer surface of the housing member.
Another aspect of the invention provides a method of attaching a connecting member to a housing member of a vacuum brake booster. The connecting member includes a cylindrical body portion having a first end and a second end. A rim portion is formed between the first end and the second end, and a stem portion is formed at the second end of the cylindrical body portion. The stem portion includes a tapered end portion. The cylindrical body portion further includes a first opening formed in the cylindrical body portion adjacent to the first end of the cylindrical body portion. The cylindrical body portion also includes a second opening in communication with the first opening. The first opening has a first diameter and the second opening has a second diameter, the second diameter being less than the first diameter. The housing member includes an inner surface, an outer surface, and a housing member opening formed therein. The stem portion is inserted through the housing member opening, and the rim portion is contacted against the housing member. The rim portion may preferably be contacted against the inner surface of the housing member. A force is applied to the stem portion. The stem portion flows radially outward thereby deforming the stem portion to create a seal between a portion of the housing member and the connecting member. A force may preferably be applied to the tapered end portion of the stem portion. The rim portion and the stem portion may preferably define a recess, and the portion of the housing member may preferably be deflected into the recess. The portion of the housing member may preferably be contacted against the rim portion, and the stem portion may preferably be contacted against the portion of the housing member. The stem portion may preferably be contacted against the outer surface of the housing member.
Another aspect of the invention provides a method of attaching a tube member to a housing member of a vacuum brake booster. A connecting member including a cylindrical body portion having a first end and a second end is provided. A rim portion is formed between the first end and the second end, and a stem portion is formed at the second end of the cylindrical body portion. The stem portion includes a tapered end portion. The cylindrical body portion further includes a first opening formed in the body portion adjacent to the first end of the cylindrical body portion, and a second opening in communication with the first opening. The first opening has a first diameter and the second opening has a second diameter, the second diameter being less than the first diameter. The tube member includes a first end portion. The housing member includes an inner surface, an outer surface, and a housing member opening formed therein. The stem portion is inserted through the housing member opening, and the rim portion is contacted against the housing member. The first end portion of the tube member is inserted into the first opening in the cylindrical body portion. A force is applied to the stem portion. The stem portion flows radially outward thereby deforming the stem portion to create a seal between a portion of the housing member and the connecting member. The rim portion is deformed against the first end portion of the tube member to fasten the tube member to the cylindrical body portion. The rim portion may preferably be deformed against the first end portion of the tube portion simultaneously with the deformation of the stem portion. A staking tool may also be provided, and may be positioned around the tube member. The first end of the cylindrical body portion my preferably be contacted against the staking tooling.